This invention relates in general to apparatus for duplicating magnetic tape and more particularly, to apparatus for simultaneously duplicating a plurality of video tapes at high speed.
The overwhelming popularity of video cassette recorders for viewing prerecorded video tapes of theatrical movies, of do it yourself video programs and the like, has created the need for a way to duplicate a master video tape onto thousands of duplicate video tapes in a fast, economical and efficient manner. Several techniques have been proposed for effecting the duplication of both audio and video tapes. The simplest technique (as disclosed, for example, in U.S. Pat. No 3,767,206, issued Oct. 23, 1973, for CASSETTE TO CASSETE DUPLICATING MEANS), provides for a master cassette tape recorder to control several similar slave recorders which duplicate the master tape onto duplicate tapes. (See also, U.S. Pat. No. 3,875,588, issued Apr. 1, 1975 for MAGNETIC TAPE DUPLICATING APPARATUS: and U.s. Pat. No. 3,928,868, issued Dec. 23, 1975, for TAPE DUPLICATING DEVICE) This technique is disadvantageous because of the expense in requiring a separate recorder for each copy of the master tape to be duplicated. Thus, in order to reproduce thousands of duplicate copies of a master tape at the same time, thousands of slave recorders must be controlled by the master recorder. The complexity and expense of such an arrangement is evident.
Another technique for duplicating magnetic tape is disclosed in U.S. Pat. No. 3,893,167, issued July 1, 1975 for MAGNETIC TAPE DUPLICATOR. As disclosed, high speed contact duplicating of a master magnetic tape is effected with a duplicate magnetic tape. This technique is disadvantageous in requiring a special master tape which has a high coercivity so that the signal on the master tape is not erased during the copying process. See also: U.s. Pat. No. 3,893,167, issued July 1, 1975, for MAGNETIC TAPE DUPLICATOR. A similar technique is disclosed in U.S. Pat. No. 3,683,123, issued Aug. 8, 1972, for METHOD OF DUPLICATING MAGNETIC RECORDING TAPES USING BOTH SURFACES OF MASTER TAPE FOR IDENTICAL SIGNALS. As disclosed in this patent, duplicate magnetic recordings are simultaneously transferred onto superimposed duplicate magnetic tapes which sandwich a master magnetic tape. The master tape has opposed surfaces, each of which carries a master recording to be duplicated. The latter technique is disadvantageous in requiring a special master tape having magnetic material on both sides.
Several duplicating techniques have centered on the use of an intermediate medium onto which a copy of the master recording is first made and a duplicate recording is made from the intermediate medium. Thus, for example, in U.S. Pat. No. 3,699,269, issued Oct. 17, 1972, for DOUBLE TRANSFER TAPE COPY SYSTEM, there is disclosed a method and apparatus for thermomagnetically and magnetically transferring short and long wavelength signals from a master magnetic tape to a pair of magnetizable layers of an intermediate carrier. The signal on the intermediate carrier is subsequently transferred to a duplicate tape. (See also U.S. Pat. No. 3,496,304 issued Feb. 17, 1970, for DOUBLE TRANSFER CURIE POINT AND MAGNETIC BIAS TAPE COPY SYSTEM reissued June 26, 1973 as Re. No. 27,685)Another intermediate transfer technique is disclosed in US Pat. No. 4,320,486 issued Mar. 16, 1982, for TRANSFERRING INFORMATION SIGNALS FROM A FIRST TO A SECOND RECORDING MEDIUM. As disclosed in this patent, information signals from a magnetic tape are reproduced and recorded onto a second magnetic tape by first recording the signals on an optical storage device, such as an optical disc. These intermediate transfer type duplicating techniques are disadvantageous in the complexity and expense of providing the intermediate transfer member.